Case Studies

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  1. 1. Name the microbe(s) Genus and species and strain if known.
  2. 2. What is the source of the microbe? (eg. feces, tap water)
    • a. What is known about attack rates?
    • b. From what sources
    • c. Add reference
  3. 3. What types of disease results from infection?
  4. 4. What are the incubation times?
    • a. Context (e.g. the context of the reference study used, such as a specific outbreak, age group, etc.)
    • b. range
    • c. median
    • d. (REF)
  5. 5. What are the morbidity rates?
    • a. Context (e.g. the context of the reference study used, such as a specific outbreak, age group, etc.)
    • b. Range
    • c. Median
    • d. Ref
  6. 6. What are the mortality rates?
    • a. Context (e.g. the context of the reference study used, such as a specific outbreak, age group, etc.)
    • b. Range
    • c. Median
    • d. Ref.
  7. 7. What are the hospitalization rates?
    • a. Source (e.g. the context of the reference study used, such as a specific outbreak, location, age group, etc.)
    • b. Range
    • c. Median
    • d. Ref.
  8. 8. Does this effect sensitive populations? Y/N
    • a. How?
  9. 9. What are excretion rates?
    • a. Concentrations per unit of bodily fluid
  10. 10. What are the secondary transmission rates?
    • a. Source (e.g. context of data used, such as transmission to family members,children in daycare centers)
    • b. Range
    • c. Median
    • d. Ref.
  11. 11. Other information

  1. 1. What is the microbe(s) used, Genus, species, strain if known.
  2. 2. What model was used?
  3. 3. Why?
  4. 4. If from the wiki add experiment # if not add reference
  5. 5. Best-fit parameters
  6. 6. Infection, morbidity and/or mortality
  7. 7. List rates used for morbidity and or mortality if applicable
    • a. References
  8. 8. Was this used in a Monte Carlo?
    • What distribution and ranges?
    • If a two parameter model is used, what is the covariance between the parameters?
    • Were confidence limits used?
    • What were the simplified assumptions used?
  9. 9. Was a new DR model calculated for this Case study?
    • a. Add data used for the model (table form from DR)

  1. 1. What is (are) the exposure scenario(s)?
  2. 2. What are the sources, pathways and routes of exposure?
    • Note that source refers to the origin; route of exposure refers to the route of transmission
    • What is the exposure media?
  3. 3. What are the exposed populations and subpopulations?
  4. 4. Identify the concentrations, durations and frequencies of the exposure?
    • Is this data taken from modeling or measurement?
  5. 5. What exposure model framework was used? What exposure modeling approach is required?
    • - What environmental factors should be taken into consideration?
    • - Are you modeling fate and transport?
    • - Are you considering inactivation and/or growth?
    • What rates are you intake; and exposure pathway refers to route of transmission using?
    • What are the references for this information?
  6. 6. What are the sources of variability in the exposure assessment?
    • What distribution and confidence range surround these estimates?
    • What are the references for this information?
  7. 7. What are the sources of uncertainty in the exposure assessment?
  8. 8. What other information will be used?
  9. 9. What is the end result of the exposure model? i.e. distribution of estimates, point values, etc.

  1. What is the best estimate of the risk (or risks)?
    • What is the range of plausible risk estimates?

  2. Provide a table of input values (from dose-response and exposure assessments).
    • What are the sources and assumptions for each value?
    • Upload the spreadsheet used for the model.

  3. What inputs contribute the most to the uncertainty in the risk estimate?
    • Provide results of sensitivity analyses

  4. What might be done to reduce uncertainties in these inputs?

  5. What subgroups may suffer disproportionately?
    • What are risks for these subgroups?

  6. How does risk differ under alternate scenarios or model assumptions?
    • - Which assumptions have the most influence on results? (i.e. provide report generated by Crystal Ball or trial and error results from changing input values)
    • - How might the validity of these assumptions be assessed?

  1. 1. Does an established acceptable level of risk exist? What is it? Where did it come from?
  2. 2. What actions can be taken to reduce the risk? What are the options or alternatives for controlling the risk?
    • How much reduction is achieved by each alternative or the chosen alternative?
    • What were the sources used for these quantities?
  3. 3. Did you consider tradeoffs between risks, benefits and costs?
  4. 4. What are the other (i.e. the social, cultural, political, and economic) considerations associated with the possible risk management decisions?
  5. 5. What are the likely impacts of the risk management decisions?
  6. 6. What is the best strategy for risk communication?
    • -Who is the audience? What are their perceptions of the risk?
    • What information needs to be communicated? Who should the communication come from?
    • What method of communication should be used (i.e. brochure, radio, television, etc.)?
  7. 7. We might ask what stakeholder engagement efforts are proposed and might even ask them to respond to these three evaluation questions:
    1. 1. Is communication two-way?
    2. 2. Are substantive issues up for negotiation?
    3. 3. Is the process evaluated?


Past QMRA Workshop Case Studies

Title Organism Exposure Authors Editor
Case Study Template
High Tech Fomites Influenza A Fomites/Surfaces Silvestri, E. Panzl, B. Prasad, B. DeFlorio, S. Adell, A. Van Leuken, J. Mark H. Weir
Cholera in Haiti V. cholerae Bui, A. Reyes, F. Foster, J. Gentry, J. Limayem, A. Lopez, J. Stott, R.
Norovirus in Drinking Water Norovirus Drinking Water Leak, E. Abla, M. Meschke, S. Jackson, C. Pogreba-Brown, K. Eltholth, M.
Boil Water Advisory Campylobacter and Cryptosporidium Drinking Water Pitkanen, T. Agullo, M. Veen, M. Habib, I. Krojgaard, L. Phi, V.
Q-Fever in Air Coxiella Burnetii Outside Air (Aerosalized pathogens) Christensen, S., Donocik, A., Gkogka, E., Katuzika, A., Velten, S. & Zurbruegg, R. Supervisor: Swart, A.N.
Drainage of Urban Water Cryptosporidium Recreational Water Mezule, L. Hamzah, F. Vang, O. Ortells, H. Verhaelen K. Nino, G.
Tularemia in Water Francisella tularensis Drinking Water Mendoza-Sanchez, I. Simmons, F. O'Donnell, C. Sato, M. Rajic, A. Mayer, B. Jenkins, A. Rose, J. Medema.

QMRAII Workshop Case Studies

Title Organism Exposure Authors
Case Study 1: Safe Drinking Water Giardia Interaction of POU devices and secondary transmission Marcel Oliveira Bataiero, Daniel Gerrity, Rafael Rasse, Daniele Vital, Radhika Dhingra. Advisors: Jade Mitchell, Marisa Mazari
Case Study 2: Biosolids Ascaris, Enterovirus, Salmonella Biosolids A Arnesen, L Casanova, J Husserl, K Newman, K Pinto, C Rock. Advisors: C Gerba, P Gurian, M Sato
Case Study 3: Emerging & Zoonotic Pathogens Toxoplasma gondii Child risk of infection with Toxoplasma gondii via drinking water in Brazil Ana E. Escalante, Caroline Rigotto, Ethell Vereen, Maureen Kinyua, Milagro Fernández-Delgado. Advisors: Maria Tereza Razzolini, Charles N. Haas
Case Study 4: Recreational Waters Enterococci Recreational water - marine water Ana C Espinosa Garcia, Eliana Suzuki, Irma N G Rivera, Kristen Pogreba-Brown, Marc Paul Verhougstraete, Maria Elisa Magri. Advisors: Joseph Eisenberg, Walter Betancourt
Case Study 5: Reclaimed Water Norovirus and E.coli Lettuce Rabia Chaudhry, Kerry Hamilton, Alejandra Fonseca, Andrezza Fernandes and Jonathan Sexton. Advisors:Joan Rose and Michel Ryan




This page is intended as a structural template for editors to use in adding their own case studies to the wiki.

The Problem

This section describes the scenario you are going to be modeling. This could in paragraph format describing a real world question health professionals or policy makers may need to know.

Template Table

Header 1 Header 2 Header 3 Header 4
Item 1 Item 2a
Item 2b
Item 3
Item 4 Item 5 Item 6

Template Image

Cell-ecoli.gif

Hazard ID

This section is where you can research the pathogens you may be encountering in this scenario. In some cases you may know ahead of time which specific pathogen you are modeling. In other cases it will be more variable based on the particular environment. You may even be dealing with multiple organisms. Once the organisms are known, research them to determine transmission routes, case-fatality ratios, epidemiological histories, etc. More information on this section is available at the hazard identification home page.

Exposure Assessment

In this section, you explore every pathway the pathogen can take from source to host. It can take considerable time, research and creativity to accurately model all the relevant parts. More information on this section is available at the exposure assessment home page.

Dose Response

This is the more mathematically intensive of the sections. Here you establish the type of model you will apply once you finish the exposure and hazard id. There are two basic equations you could use and countless possibilities for the variables. More explanation and a compilation of dose-response models is available at the dose-response home page

Risk Characterization

Once the exposures are understood and the dose-response relationship is known you can then put these parts together to provide a probability of infection based on a single time period or incidence. For more information and additional examples, visit the risk characterization home page.

Risk Management

Now that you know the nature of the risk, you can start to explore the various methods of reducing that risk. While this appears to be a more traditional form of environmental health, pairing it with the risk assessment framework you will know have an well developed idea of what parts of the infection chain would be most appropriate to target. This would be either because a certain part contributes a considerable amount of risk or because it is easily addressed. Also part of risk management is mathematica cost and effectiveness models that guide you as to how to carry out these management strategies. More information available at the risk management home page

References

Put all references in this section.






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